Editor—Oculocutaneous albinism type 2 (OCA2) is an autosomal recessive disorder characterised by defective melanin production of the skin, hair, and eyes,1 which is caused by mutations of the P gene.2 3The specific function of P has not been clarified, although it is likely to act as a transporter in the melanosomal membrane.2 4

The P gene is located in 15q11-q13, which is deleted in the majority of patients with Angelman syndrome (AS) and Prader-Willi syndrome (PWS).2 5 TheP gene is not imprinted and both alleles are expressed. PWS and AS patients with typical deletions are thus hemizygous for P. It is also well established that AS and PWS deletion patients usually show hypopigmentation of the skin and hair, and Pis suggested to be responsible for this hypopigmentation as well,6 7 although the mechanism has not yet been established.

A small intragenic deletion and a V443I missense mutation of theP gene were identified in the maternally inherited alleles of two PWS plus OCA2 patients who had a paternally inherited deletion of 15q11-q13.2 3 Here we describe the first evidence that a P gene mutation is responsible for OCA2 associated with AS.

The male patient was born at 38 weeks' gestation to unrelated Japanese parents. There were no complications of pregnancy or delivery, but the birth weight, 1850 g, was small for gestational dates. Generalised albinism was noted at birth. Motor development was delayed, and he had a generalised tonic-clonic convulsion at the age of 18 months. He was admitted to hospital at the …